Toán Lớp 8: (4x -1)^2 – (x + 2)^2= 0 tìm x

Question

Toán Lớp 8:  (4x -1)^2 – (x + 2)^2= 0 tìm x

ngochuong2k2 · Answer

(4x -1)&sup2; &ndash; (x + 2)&sup2;= 0     [(4x -1) - (x + 2)] . [(4x - 1) + (x + 2)] = 0   (SỬ DỤNG HĐT HIỆU HAI B&Igrave;NH PHƯƠNG)    (4x - 1 - x + 2) . ( 4x - 1 + x + 2) = 0         (Ph&aacute; ngoặc)    (3x + 1) . (5x+ 1) = 0   &rArr;  ( left[  begin{array}{l}3x +1= 0  5x+1=0 end{array}  right. )    &rArr;  ( left[  begin{array}{l}3x=-1  5x=-1 end{array}  right. )    &rArr; ( left[  begin{array}{l}x= frac{-1}{3}   x= frac{-1}{5}  end{array}  right. )    Vậy x $ in$ {$ frac{-1}{3}$; $ frac{-1}{5}$  }

aivilanlan · Answer

Giải đáp: x = -1/3 hoặc x = -1/5 Lời giải và giải thích chi tiết: (4x - 1)^2 - (x + 2)^2 = 0 <=> (4x - 1 - x + 2)(4x - 1 + x + 2) = 0 <=> (3x + 1)(5x + 1) = 0 <=> ( left[ begin{array}{l}3x+1=0 5x+1=0 end{array} right. ) <=> ( left[ begin{array}{l}3x=-1 5x=-1 end{array} right. ) <=> ( left[ begin{array}{l}x=-1/3 x=-1/5 end{array} right. ) Vậy x = -1/3 hoặc x = -1/5